GROWTH OF THE INNER EAR OF ALBINO RAT 



83 



13. The greatest height of Hensen's supporting cells. The older 

 authors (Kolliker and others) thought that the arch of Corti 

 marks the highest point of the papilla which slopes from this 

 point gradually outward to the cells of the zona pectinata. 

 Against this erroneous idea Hensen ('63) first published obser- 

 vations showing that the highest point is in the papilla which 

 ascends laterally from the outer hair cells, and then slopes 

 abruptly and passes over to the cells of the sulcus spiralis externus. 

 We term this prominence Hensen's prominence and the cells, 

 Hensen's supporting cells. The measurements of the height of 



25 50 50 100 200 300 400 50O 



Chart 25 The greatest height of Hensen's supporting cells, table 55. 



these cells were made along 3 3 in figure 1. Table 55 (chart 

 25) shows the values for the greatest vertical height of these 

 supporting cells according to age. At the foot of the last column 

 are given the ratios from 1 to 6, 1 to 12, 1 to 20, 1 to 546, 6 to 12, 

 6 to 20, 6 to 546, 12 to 20, 12 to 546, and 20 to 546 days. The 

 values diminish at the earlier stage from birth to six or nine days. 

 At twelve days they increase suddenly, more than doubling. 

 After that they increase to old age, rapidly up to twenty days 

 and then slowly. Here also the height increases from the base 

 to the apex, the most marked increase occurring between turns 

 II and III. In table 56 this relation is clearly shown. Retzius 

 ('84) gets values of this height in the rabbit and cat as follows 

 (table 57). 



